Anyone know what size ceiling joist is allowed for a 18’span. The rafter above is an 11 &7/8″ TJI. I live in Ma. and can’t find my code book. Been a while since I have done any residential work. Appreciate any help I may get!!!
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http://www.cwc.ca/design/tools/calcs/SpanCalc_2002/
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Cool calculator. The unfortunate thing is that it only lets you calculate live loads of 50 psf. Code in my location requires building for 120 psf.
On a cieling???!!!
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sounds like somebody is really into some heavy swag stuff...
shouldn't all cielings be mezzazine decks in disguise???
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Maybe this is in the land down under where they walk on the ceilings
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shouldn't all cielings be mezzazine decks in disguise?
Probably. Depending upon roof pitch, of course. A 4/12 roof that only peaks 60-something inches above the rafters would seem an unlikely canidate for a furture attic "room."
Same plan dimensions with a 9/12 or 12/12 would be a different story. At 12/12, I might even block for future kneewalls. Or not. That's the problem with generalities--they're never specific enough <g>Occupational hazard of my occupation not being around (sorry Bubba)
generally speaking....
yur right....
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
On a cieling???!!!
:-) Heh heh. It's for a top secret project. Seriously, I was thinking of snow loads on roof spans, but none of the charts go past 100 psf live load. Our loads here are 120psf and up the road a bit they go as high as 250 psf, maybe higher but I know they go to 250.
The US spans seem to be much weaker
Hube, you aren't reading the tool right. It does not say that US spans are weaker, but that US species are stronger (which sounds unlikely, but whatever). Look at the tool again. The two categories are
US Spans for Canadian Species
US Spans for US Species
The tool doesn't say anything at all about Canadian spans. Presumably those numbers would not be in psf anyway.
Edited 12/6/2004 1:35 am ET by tlambert
Edited 12/6/2004 2:10 pm ET by tlambert
Oh, ya, I'm reading the chart right ...The US spans (according to this chart) are definitely WEAKER than the Canadian.
and yes, most Canadian codes are still in the normal imperial measure. (psi, psf, etc, etc.
Edited 12/6/2004 1:52 pm ET by Hube
Hube,
Look again. The chart is not a span table for Canada. It is for US spans only, using Canadian species or US species. According to the tool Canadian species are weaker than US species, but it says nothing at all about Canadian spans.
Look at the label: "SpanCalc: a US span calculator for major lumber species". If you click on the "more info link" it says:
This on-line utility provides a convenient reference for spans for common species of Canadian and U.S. dimension lumber, fully in accord with United States building codes and Federal Housing Administration [FHA] requirements.
The information provided by this utility applies only in the United States.
Edited 12/6/2004 2:17 pm ET by tlambert
But I have all the Canadian bldg codes right here and all up to current date. And compared to this US chart, the Canadian code spans will allow for a much stronger effect in comparison to the weaker US spans..
Okay, I get it. I thought you were talking about the two sets of values listed on that tool in the link.
Boy, o boy, according to this chart there sure is a great difference between US and Canadian spans. The US spans seem to be much weaker as they allow for greater spans than Can. codes do. I know the US gallon is only 4/5 of a Can. gallon, but I think the 1 foot measure in both countrys is still 12", lol
Edited 12/5/2004 10:10 am ET by Hube
Those Canadadians do have higher requirements, especially for snow loads
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that's it.....
inverted application....
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
You all better leave member sizing to someone who knows whats going on!! The snow load for Yukatat, Alaska is 150 psf.
"You all better leave member sizing to someone who knows whats going on!! The snow load for Yukatat, Alaska is 150 psf."Sure, but when you're thinking through plans or something, it woudl be nice to get a rough idea of what you're getting into *before* shelling out the $2/sf for the structural engineer to see if you're even in the ballpark.